Evidence of Evolution

Comparative Embryology

Comparative anatomy

Observable Examples of Evolution

Lamarck

Jean Baptiste Lamarck (1744- 1829) Often known simply as Lamarck, was a French naturalist. He was a soldier, biologist, academic, and an early proponent of the idea that evolution occurred and proceeded in accordance with natural laws. He is widely remembered for a theory of inheritance of acquired characteristics, called soft inheritance, Lamarckism or use/disuse theory that he described in 1801.

Lamarck stressed two main themes in his biological work. The first was that the environment gives rise to changes in animals. He cited examples of blindness in moles, the presence of teeth in mammals and the absence of teeth in birds as evidence of this principle. The second principle was that life was structured in an orderly manner and that many different parts of all bodies make it possible for the organic movements of animals.

NeedOrganisms strive to better themselves and become more successful. (Change based on necessity)

Use and DisuseThe more a structure is used, the more it develops. If a structure is not used it will waste away and eventually disappear.

Inheritance of acquired traits Once a structure/trait is modified by use or disuse the modification is passed along to its offspring.

Weismann

August Weismann is known for the experiments he conducted on mice in 1891.

In a famous series of experiments in which he cut off the tails of mice for 22 generations, Weismanndisproved the theory that acquired characteristics could be inherited.

Weismann conducted the experiment of removing the tails of 68 white mice, repeatedly over 5 generations, and reporting that no mice were born in consequence without a tail or even with a shorter tail. He stated that "901 young were produced by five generations of artificially mutilated parents and yet there was not a single example of a rudimentary tail or any other abnormality of the organ"

Darwin

Overproduction

Variation

Competition

Natural Selection

SPeciation

Geographic isolation

reproductive isolation

Origin of life

The Heterotroph Hypothesis

The earliest cells were probably heterotrophs. Most likely they got their energy from other molecules in the organic “soup.” However, by about 3 billion years ago, a new way of obtaining energy evolved. This new way was photosynthesis. Through photosynthesis, organisms could use sunlight to make food from carbon dioxide and water. These organisms were the first autotrophs. They provided food for themselves and for other organisms that began to consume them. After photosynthesis evolved, oxygen started to accumulate in the atmosphere. This has been dubbed the “oxygen catastrophe.” Why? Oxygen was toxic to most early cells because they had evolved in its absence. As a result, many of them died out. The few that survived evolved a new way to take advantage of the oxygen. This second major innovation was cellular respiration. It allowed cells to use oxygen to obtain more energy from organic molecules.